I am certain that you cannot claim copyright for a brush based on a skull used as part of a bands logo (namely combichrist) as I am sure you did not get their permission to use the skull to begin with.
copyright the exclusive legal right to reproduce, publish, sell, or distribute the matter and form of something (as a literary, musical, or artistic work)
copyright
the exclusive legal right to reproduce, publish, sell, or distribute the matter and form of something (as a literary, musical, or artistic work)